Manufacture of threads from viscose.



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I THOMAS H. VERHAVE, OF THE HAGUE, NETHERLANDS.

MANUFACTURE or 'rnnnans mom VISCOSE.

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No Drawing.

, Z}? all whom it may concern:

and useful Manufacture of Threads from Viscose;and I do hereby declare the following to be a full, clear, and exact description of the same. I

It is known that good shiny artificial silkthreads can be'obtained-from viscose only after the :latter. has been .standing some time. The molecules of cellulose xanthogenatej then coalesce, a process which is known as the ripening of theviscose. The more .the viscose is ripened or seasoned either by a long ripening process, or by sub- JeCtiiIg it to a high temperature, the more satisfactory is the precipltation. If ripened sufliciently, the precipitation takes place spontaneously. w

It has been found that viscose which has i been kept for 'Zto 8 days at a temperature of 16, is the most suitable for spinning.

Such viscose requires for its precipitation only a verysmall quantity of free hydrogen ions, which has the advantage that the newly formed thread, when escaping from the spinning nozzle, is not damaged by an excessive. concentration'of acid during its travel through the spinning bath. If, how- 7, ever the-viscose contains a'large quantity of free soda-lye in order to form a sufficiently thin'fiuid, an alkalineireaction of the spin- 'ningibath would. soon take place. A good "spinningj bath must therefore have a low concentrationof hydrogen ions. The con- '-1 centratioir'must however remain constant to hydroxyl ions-of the-viscose.

and therefore it must lac-automatically re newed as" neutralization is efl'eoted by the m H I man Patents Nos. 2408416 and 2604179.

1 ,This result can be obtained in various according to this mvention, for a viscose ofl ways, for instance by dissolving a weak or'by dissolving a strong acidin-an organic liquid which has a small [ionizing action;

' :or finally by dissolving a strong acid in a nula is medium having a good ionizing action and by restraining the ionizing of the acid which takes place according to the known formula of equilibrium. For sulfuric acid this for- H SO 2HSO,

In order to restrain the ionizing, there- I fore, it is necessary to' add a larger quantity Specification of Letters Patent.

- Application filed February 23, 1915. Serial no; 9,916.

' or in other words it is necessar Patented ca. 11, rate.

of SO ions to the solution of sulfuric acid, to add a substance which in an aqueous iquid produces an ample quantity of SO ions, but no H-ions, that is to say a sulfate. This possibility is however precluded by the limited solubility of the said salts. Thus for instance the spinning bath described in German Patent No. 187947," with a viscose of -the degree of ripeness described, produces a dull weak thread, Which m0re0ver is re-' ferred to in German Patent No. 2408445,

lines 20 to 22, and' in other literature. This is due to the quantity of the existing'SO ions being still insufficient, compared to the proportion of hydrogen ions. In order to restrain sufiiciently the ionizing of the acid, still more sodium sulfate should be dissolved, which however is not possible owing to the limited solubility of sodium sulfate.

According to this invention, this disadvantage is obviated by dissolving in the liquid an additional quantity ofsulfate, in order to increase sufiiciently the concentration of the S0 ions. In the case of a proportion of about 10% of sulfuric acid, the concentration should be at least 3 grammolecules per kilogram of the spinning bath, that is to say 3 molecules of SO ions should be present to each two molecules of'hydro' I In thexspinning bathdescribed in German Patentt'g hlo 187947' ;tl 1e revv are only 313 molecules of ions toteach 3 molecules -of H'-.IlQl1S andthe same} conditions are roumtzin; the process described in the Grer- A suitable composition of aspinning bath the above mentioned degree of ripeness is for instance as follows:

16 parts Na; S0

30 parts crystallized magnesium sulfate MgSO ZI-LO,

45 parts water.

Thesalts 'could be however replaced'by soluble sulfates added in such quantity to at an aqueous solution of sulfuric-acid of not materially less than 7 per-cent, that the resultant solution contains at least 3 mol.

5 S0 ions to each 2mol.-H-ions.

2. In the manufacture of threads from Viscose, the introduction of the latter into a spinning bath which contains a plurality of easily-soluble sulfates added in such 10 quantity to an aqueous solution of sulfuric acid of not materially less than 7 per-cent, that the resultant solution contains at least 3 mol. SO ions to each 2 mol. H-ions.

In testimony whereof I have signed my name to this specification in the-presence of 15 two subscribing witnesses.

THOMAS H VERHAVE.

Witnesses:

NICOLAAS J. C. HOLDEMAN, KUUN WIJNBRAUS. 

